1 files changed, 94 insertions, 149 deletions

diff --git a/fs/ubifs/budget.c b/fs/ubifs/budget.c
index 4a18f084cc42..f393620890ee 100644
--- a/fs/ubifs/budget.c
+++ b/fs/ubifs/budget.c
@@ -32,18 +32,15 @@
 
 #include "ubifs.h"
 #include <linux/writeback.h>
-#include <asm/div64.h>
+#include <linux/math64.h>
 
 /*
  * When pessimistic budget calculations say that there is no enough space,
  * UBIFS starts writing back dirty inodes and pages, doing garbage collection,
- * or committing. The below constants define maximum number of times UBIFS
+ * or committing. The below constant defines maximum number of times UBIFS
  * repeats the operations.
  */
-#define MAX_SHRINK_RETRIES 8
-#define MAX_GC_RETRIES     4
-#define MAX_CMT_RETRIES    2
-#define MAX_NOSPC_RETRIES  1
+#define MAX_MKSPC_RETRIES 3
 
 /*
  * The below constant defines amount of dirty pages which should be written
@@ -52,30 +49,6 @@
 #define NR_TO_WRITE 16
 
 /**
- * struct retries_info - information about re-tries while making free space.
- * @prev_liability: previous liability
- * @shrink_cnt: how many times the liability was shrinked
- * @shrink_retries: count of liability shrink re-tries (increased when
- *                  liability does not shrink)
- * @try_gc: GC should be tried first
- * @gc_retries: how many times GC was run
- * @cmt_retries: how many times commit has been done
- * @nospc_retries: how many times GC returned %-ENOSPC
- *
- * Since we consider budgeting to be the fast-path, and this structure has to
- * be allocated on stack and zeroed out, we make it smaller using bit-fields.
- */
-struct retries_info {
-        long long prev_liability;
-        unsigned int shrink_cnt;
-        unsigned int shrink_retries:5;
-        unsigned int try_gc:1;
-        unsigned int gc_retries:4;
-        unsigned int cmt_retries:3;
-        unsigned int nospc_retries:1;
-};
-
-/**
  * shrink_liability - write-back some dirty pages/inodes.
  * @c: UBIFS file-system description object
  * @nr_to_write: how many dirty pages to write-back
@@ -147,13 +120,29 @@ static int run_gc(struct ubifs_info *c)
 }
 
 /**
+ * get_liability - calculate current liability.
+ * @c: UBIFS file-system description object
+ *
+ * This function calculates and returns current UBIFS liability, i.e. the
+ * amount of bytes UBIFS has "promised" to write to the media.
+ */
+static long long get_liability(struct ubifs_info *c)
+{
+        long long liab;
+
+        spin_lock(&c->space_lock);
+        liab = c->budg_idx_growth + c->budg_data_growth + c->budg_dd_growth;
+        spin_unlock(&c->space_lock);
+        return liab;
+}
+
+/**
  * make_free_space - make more free space on the file-system.
  * @c: UBIFS file-system description object
- * @ri: information about previous invocations of this function
  *
  * This function is called when an operation cannot be budgeted because there
  * is supposedly no free space. But in most cases there is some free space:
- *   o budgeting is pessimistic, so it always budgets more then it is actually
+ *   o budgeting is pessimistic, so it always budgets more than it is actually
  *     needed, so shrinking the liability is one way to make free space - the
  *     cached data will take less space then it was budgeted for;
  *   o GC may turn some dark space into free space (budgeting treats dark space
@@ -165,87 +154,42 @@ static int run_gc(struct ubifs_info *c)
  * Returns %-ENOSPC if it couldn't do more free space, and other negative error
  * codes on failures.
  */
-static int make_free_space(struct ubifs_info *c, struct retries_info *ri)
+static int make_free_space(struct ubifs_info *c)
 {
-        int err;
+        int err, retries = 0;
+        long long liab1, liab2;
 
-        /*
-         * If we have some dirty pages and inodes (liability), try to write
-         * them back unless this was tried too many times without effect
-         * already.
-         */
-        if (ri->shrink_retries < MAX_SHRINK_RETRIES && !ri->try_gc) {
-                long long liability;
-
-                spin_lock(&c->space_lock);
-                liability = c->budg_idx_growth + c->budg_data_growth +
-                            c->budg_dd_growth;
-                spin_unlock(&c->space_lock);
-
-                if (ri->prev_liability >= liability) {
-                        /* Liability does not shrink, next time try GC then */
-                        ri->shrink_retries += 1;
-                        if (ri->gc_retries < MAX_GC_RETRIES)
-                                ri->try_gc = 1;
-                        dbg_budg("liability did not shrink: retries %d of %d",
-                                 ri->shrink_retries, MAX_SHRINK_RETRIES);
-                }
-
-                dbg_budg("force write-back (count %d)", ri->shrink_cnt);
-                shrink_liability(c, NR_TO_WRITE + ri->shrink_cnt);
+        do {
+                liab1 = get_liability(c);
+                /*
+                 * We probably have some dirty pages or inodes (liability), try
+                 * to write them back.
+                 */
+                dbg_budg("liability %lld, run write-back", liab1);
+                shrink_liability(c, NR_TO_WRITE);
 
-                ri->prev_liability = liability;
-                ri->shrink_cnt += 1;
-                return -EAGAIN;
-        }
+                liab2 = get_liability(c);
+                if (liab2 < liab1)
+                        return -EAGAIN;
 
-        /*
-         * Try to run garbage collector unless it was already tried too many
-         * times.
-         */
-        if (ri->gc_retries < MAX_GC_RETRIES) {
-                ri->gc_retries += 1;
-                dbg_budg("run GC, retries %d of %d",
-                         ri->gc_retries, MAX_GC_RETRIES);
+                dbg_budg("new liability %lld (not shrinked)", liab2);
 
-                ri->try_gc = 0;
+                /* Liability did not shrink again, try GC */
+                dbg_budg("Run GC");
                 err = run_gc(c);
                 if (!err)
                         return -EAGAIN;
 
-                if (err == -EAGAIN) {
-                        dbg_budg("GC asked to commit");
-                        err = ubifs_run_commit(c);
-                        if (err)
-                                return err;
-                        return -EAGAIN;
-                }
-
-                if (err != -ENOSPC)
-                        return err;
-
-                /*
-                 * GC could not make any progress. If this is the first time,
-                 * then it makes sense to try to commit, because it might make
-                 * some dirty space.
-                 */
-                dbg_budg("GC returned -ENOSPC, retries %d",
-                         ri->nospc_retries);
-                if (ri->nospc_retries >= MAX_NOSPC_RETRIES)
+                if (err != -EAGAIN && err != -ENOSPC)
+                        /* Some real error happened */
                         return err;
-                ri->nospc_retries += 1;
-        }
 
-        /* Neither GC nor write-back helped, try to commit */
-        if (ri->cmt_retries < MAX_CMT_RETRIES) {
-                ri->cmt_retries += 1;
-                dbg_budg("run commit, retries %d of %d",
-                         ri->cmt_retries, MAX_CMT_RETRIES);
+                dbg_budg("Run commit (retries %d)", retries);
                 err = ubifs_run_commit(c);
                 if (err)
                         return err;
-                return -EAGAIN;
-        }
+        } while (retries++ < MAX_MKSPC_RETRIES);
+
         return -ENOSPC;
 }
 
@@ -258,8 +202,8 @@ static int make_free_space(struct ubifs_info *c, struct retries_info *ri)
  */
 int ubifs_calc_min_idx_lebs(struct ubifs_info *c)
 {
-        int ret;
-        uint64_t idx_size;
+        int idx_lebs, eff_leb_size = c->leb_size - c->max_idx_node_sz;
+        long long idx_size;
 
         idx_size = c->old_idx_sz + c->budg_idx_growth + c->budg_uncommitted_idx;
 
@@ -271,23 +215,16 @@ int ubifs_calc_min_idx_lebs(struct ubifs_info *c)
          * pair, nor similarly the two variables for the new index size, so we
          * have to do this costly 64-bit division on fast-path.
          */
-        if (do_div(idx_size, c->leb_size - c->max_idx_node_sz))
-                ret = idx_size + 1;
-        else
-                ret = idx_size;
+        idx_size += eff_leb_size - 1;
+        idx_lebs = div_u64(idx_size, eff_leb_size);
         /*
          * The index head is not available for the in-the-gaps method, so add an
          * extra LEB to compensate.
          */
-        ret += 1;
-        /*
-         * At present the index needs at least 2 LEBs: one for the index head
-         * and one for in-the-gaps method (which currently does not cater for
-         * the index head and so excludes it from consideration).
-         */
-        if (ret < 2)
-                ret = 2;
-        return ret;
+        idx_lebs += 1;
+        if (idx_lebs < MIN_INDEX_LEBS)
+                idx_lebs = MIN_INDEX_LEBS;
+        return idx_lebs;
 }
 
 /**
@@ -530,8 +467,7 @@ static int calc_dd_growth(const struct ubifs_info *c,
 int ubifs_budget_space(struct ubifs_info *c, struct ubifs_budget_req *req)
 {
         int uninitialized_var(cmt_retries), uninitialized_var(wb_retries);
-        int err, idx_growth, data_growth, dd_growth;
-        struct retries_info ri;
+        int err, idx_growth, data_growth, dd_growth, retried = 0;
 
         ubifs_assert(req->new_page <= 1);
         ubifs_assert(req->dirtied_page <= 1);
@@ -549,7 +485,6 @@ int ubifs_budget_space(struct ubifs_info *c, struct ubifs_budget_req *req)
         if (!data_growth && !dd_growth)
                 return 0;
         idx_growth = calc_idx_growth(c, req);
-        memset(&ri, 0, sizeof(struct retries_info));
 
 again:
         spin_lock(&c->space_lock);
@@ -587,12 +522,17 @@ again:
                 return err;
         }
 
-        err = make_free_space(c, &ri);
+        err = make_free_space(c);
+        cond_resched();
         if (err == -EAGAIN) {
                 dbg_budg("try again");
-                cond_resched();
                 goto again;
         } else if (err == -ENOSPC) {
+                if (!retried) {
+                        retried = 1;
+                        dbg_budg("-ENOSPC, but anyway try once again");
+                        goto again;
+                }
                 dbg_budg("FS is full, -ENOSPC");
                 c->nospace = 1;
                 if (can_use_rp(c) || c->rp_size == 0)
@@ -666,7 +606,7 @@ void ubifs_release_budget(struct ubifs_info *c, struct ubifs_budget_req *req)
  * @c: UBIFS file-system description object
  *
  * This function converts budget which was allocated for a new page of data to
- * the budget of changing an existing page of data. The latter is smaller then
+ * the budget of changing an existing page of data. The latter is smaller than
  * the former, so this function only does simple re-calculation and does not
  * involve any write-back.
  */
@@ -712,9 +652,9 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c,
  * user-space. User-space application tend to expect that if the file-system
  * (e.g., via the 'statfs()' call) reports that it has N bytes available, they
  * are able to write a file of size N. UBIFS attaches node headers to each data
- * node and it has to write indexind nodes as well. This introduces additional
- * overhead, and UBIFS it has to report sligtly less free space to meet the
- * above expectetion.
+ * node and it has to write indexing nodes as well. This introduces additional
+ * overhead, and UBIFS has to report slightly less free space to meet the above
+ * expectations.
  *
  * This function assumes free space is made up of uncompressed data nodes and
  * full index nodes (one per data node, tripled because we always allow enough
@@ -723,7 +663,7 @@ void ubifs_release_dirty_inode_budget(struct ubifs_info *c,
  * Note, the calculation is pessimistic, which means that most of the time
  * UBIFS reports less space than it actually has.
  */
-long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free)
+long long ubifs_reported_space(const struct ubifs_info *c, long long free)
 {
         int divisor, factor, f;
 
@@ -737,7 +677,7 @@ long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free)
          * of data nodes, f - fanout. Because effective UBIFS fanout is twice
          * as less than maximum fanout, we assume that each data node
          * introduces 3 * @c->max_idx_node_sz / (@c->fanout/2 - 1) bytes.
-         * Note, the multiplier 3 is because UBIFS reseves thrice as more space
+         * Note, the multiplier 3 is because UBIFS reserves thrice as more space
          * for the index.
          */
         f = c->fanout > 3 ? c->fanout >> 1 : 2;
@@ -745,45 +685,33 @@ long long ubifs_reported_space(const struct ubifs_info *c, uint64_t free)
         divisor = UBIFS_MAX_DATA_NODE_SZ;
         divisor += (c->max_idx_node_sz * 3) / (f - 1);
         free *= factor;
-        do_div(free, divisor);
-        return free;
+        return div_u64(free, divisor);
 }
 
 /**
- * ubifs_get_free_space - return amount of free space.
+ * ubifs_get_free_space_nolock - return amount of free space.
  * @c: UBIFS file-system description object
  *
  * This function calculates amount of free space to report to user-space.
  *
  * Because UBIFS may introduce substantial overhead (the index, node headers,
- * alighment, wastage at the end of eraseblocks, etc), it cannot report real
+ * alignment, wastage at the end of eraseblocks, etc), it cannot report real
  * amount of free flash space it has (well, because not all dirty space is
- * reclamable, UBIFS does not actually know the real amount). If UBIFS did so,
- * it would bread user expectetion about what free space is. Users seem to
+ * reclaimable, UBIFS does not actually know the real amount). If UBIFS did so,
+ * it would bread user expectations about what free space is. Users seem to
  * accustomed to assume that if the file-system reports N bytes of free space,
  * they would be able to fit a file of N bytes to the FS. This almost works for
  * traditional file-systems, because they have way less overhead than UBIFS.
  * So, to keep users happy, UBIFS tries to take the overhead into account.
  */
-long long ubifs_get_free_space(struct ubifs_info *c)
+long long ubifs_get_free_space_nolock(struct ubifs_info *c)
 {
-        int min_idx_lebs, rsvd_idx_lebs, lebs;
+        int rsvd_idx_lebs, lebs;
         long long available, outstanding, free;
 
-        spin_lock(&c->space_lock);
-        min_idx_lebs = ubifs_calc_min_idx_lebs(c);
+        ubifs_assert(c->min_idx_lebs == ubifs_calc_min_idx_lebs(c));
         outstanding = c->budg_data_growth + c->budg_dd_growth;
-
-        /*
-         * Force the amount available to the total size reported if the used
-         * space is zero.
-         */
-        if (c->lst.total_used <= UBIFS_INO_NODE_SZ && !outstanding) {
-                spin_unlock(&c->space_lock);
-                return (long long)c->block_cnt << UBIFS_BLOCK_SHIFT;
-        }
-
-        available = ubifs_calc_available(c, min_idx_lebs);
+        available = ubifs_calc_available(c, c->min_idx_lebs);
 
         /*
          * When reporting free space to user-space, UBIFS guarantees that it is
@@ -796,15 +724,14 @@ long long ubifs_get_free_space(struct ubifs_info *c)
          * Note, the calculations below are similar to what we have in
          * 'do_budget_space()', so refer there for comments.
          */
-        if (min_idx_lebs > c->lst.idx_lebs)
-                rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
+        if (c->min_idx_lebs > c->lst.idx_lebs)
+                rsvd_idx_lebs = c->min_idx_lebs - c->lst.idx_lebs;
         else
                 rsvd_idx_lebs = 0;
         lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
                c->lst.taken_empty_lebs;
         lebs -= rsvd_idx_lebs;
         available += lebs * (c->dark_wm - c->leb_overhead);
-        spin_unlock(&c->space_lock);
 
         if (available > outstanding)
                 free = ubifs_reported_space(c, available - outstanding);
@@ -812,3 +739,21 @@ long long ubifs_get_free_space(struct ubifs_info *c)
                 free = 0;
         return free;
 }
+
+/**
+ * ubifs_get_free_space - return amount of free space.
+ * @c: UBIFS file-system description object
+ *
+ * This function calculates and retuns amount of free space to report to
+ * user-space.
+ */
+long long ubifs_get_free_space(struct ubifs_info *c)
+{
+        long long free;
+
+        spin_lock(&c->space_lock);
+        free = ubifs_get_free_space_nolock(c);
+        spin_unlock(&c->space_lock);
+
+        return free;
+}